Photosensitive compositions are prepared by adding a photopolymerization initiator to a polymerizable compound having at least one ethylenically unsaturated bond. Because such photosensitive compositions can be cured through polymerization through irradiation with energy rays (light), they are used, for example, in photocurable inks, photosensitive printing plates, and various types of photoresists.
The following Patent Documents 1 to 11 propose the use of oxime ester compounds as photopolymerization initiators used for photosensitive compositions.
While some of the oxime ester compounds disclosed in those Patent Documents have satisfactory sensitivity, such oxime ester compounds unfortunately have poor transmittance in the visible region and thus cannot provide the desired colors when used in color filters. (Particularly in transparent photosensitive compositions, such as protection films, and in color-filter resists containing blue pigments or colorants, the brightness and color purity deteriorate in cases where compounds having absorption in the range of 380 to 450 nm are mixed.) On the other hand, oxime ester compounds having high transmittance in the visible region are, in turn, unsatisfactory in terms of sensitivity. Thus, there has been a demand for a photopolymerization initiator having both satisfactory sensitivity and high transmittance in the visible region.
Meanwhile, high sensitivity is demanded of alkali-developable, colored photosensitive resin compositions containing colorants, such as color filers, which thus calls for high photopolymerization-initiator concentrations in resists.
High concentrations of photopolymerization initiators, however, give rise to residues due to deterioration in developability and cause contamination of photomasks and heating furnaces due to sublimed products.
Citation List
Patent Document
Patent Document 1: JP-A-2000-80068 (U.S. Pat. No. 6,596,445)
Patent Document 2: JP-A-2001-233842 (U.S. Pat. No. 6,949,678)
Patent Document 3: JP-A-2001-302871
Patent Document 4: JP-T-2004-534797 (U.S. Pat. No. 7,189,489)
Patent Document 5: JP-A-2005-25169
Patent Document 6: JP-A-2005-128483
Patent Document 7: JP-A-2005-242279
Patent Document 8: JP-A-2005-242280
Patent Document 9: JP-A-2006-16545
Patent Document 10: JP-A-2008-3164
Patent Document 11: Japanese Patent No. 3,754,065